Radio frequency field inhomogeneity correction method, apparatus, electronic device, and program product

Abstract

The application is suitable for the field of magnetic resonance imaging technology, and provides a radio frequency field inhomogeneity correction method and device, electronic equipment and program product. The method comprises the following steps: acquiring actual radio frequency field intensity of each position in a scanning object under two preset radio frequency field intensities, and actual CEST signal intensity at a first chemical shift and a second chemical shift; determining a first ideal CEST signal intensity based on the actual radio frequency field intensity of the same position under the two preset radio frequency field intensities and the actual CEST signal intensity at the first chemical shift; determining a second ideal CEST signal intensity based on the actual radio frequency field intensity of the same position under the two preset radio frequency field intensities and the actual CEST signal intensity at the second chemical shift; and determining a GluCEST signal intensity based on the above two ideal CEST signal intensities of the same position under a target radio frequency field intensity. The application can improve the accuracy of GluCEST signal intensity measurement.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of magnetic resonance imaging, and particularly relates to a radio frequency field inhomogeneity correction method and device, electronic equipment and program product. BACKGROUND

[0002] Chemical Exchange Saturation Transfer (CEST) imaging is a molecular imaging technique with high sensitivity, which can detect endogenous metabolites, compounds (such as glutamate, glycogen, amide protons, etc.) in the microenvironment of the tissue and exogenous paramagnetic / diamagnetic CEST contrast agents. By selectively saturating the exchangeable protons in the target molecule, the change in the magnetization strength of the free water is observed, thereby indirectly reflecting the content and chemical exchange rate of the target molecule. Glutamate is a major neurotransmitter that plays a key role in maintaining the normal function of the central nervous system. Glutamate CEST (GluCEST) imaging visualizes glutamate by detecting the chemical exchange between the amine protons in glutamate and free water. Since the chemical exchange rate of amine protons is relatively fast under physiological temperature and pH conditions, GluCEST imaging must be performed at high magnetic field strength. However, the high-field clinical scanner has obvious radio frequency field (B1) inhomogeneity, which affects the accuracy of GluCEST signal intensity measurement. SUMMARY

[0003] The embodiments of the present application provide a radio frequency field inhomogeneity correction method, device, electronic equipment and program product, which can improve the accuracy of GluCEST signal intensity measurement.

[0004] In a first aspect, the embodiments of the present application provide a radio frequency field inhomogeneity correction method, comprising:

[0005] In the case where the radio frequency field strength is a first preset radio frequency field strength, acquiring a first actual radio frequency field strength at each position in a scanning object, a first actual Chemical Exchange Saturation Transfer (CEST) signal strength at a first chemical shift and a second actual CEST signal strength at a second chemical shift, the first chemical shift being a chemical shift of glutamate, and the second chemical shift being a chemical shift opposite to the water molecule relative to the glutamate;

[0006] In the case where the radio frequency field strength is a second preset radio frequency field strength, acquiring a second actual radio frequency field strength at each position in the scanning object, a third actual CEST signal strength at the first chemical shift and a fourth actual CEST signal strength at the second chemical shift, the second preset radio frequency field strength being different from the first preset radio frequency field strength;

[0007] determine a first ideal CEST signal intensity of the corresponding position at the target radio frequency field strength at the first chemical shift based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity and the third actual CEST signal intensity at the same position;

[0008] determine a second ideal CEST signal intensity of the corresponding position at the target radio frequency field strength at the second chemical shift based on the first actual radio frequency field intensity, the second actual CEST signal intensity, the second actual radio frequency field intensity and the fourth actual CEST signal intensity at the same position;

[0009] determine a glutamate (Glu) CEST signal intensity of the corresponding position at the target radio frequency field strength based on the first ideal CEST signal intensity and the second ideal CEST signal intensity of the corresponding position at the target radio frequency field strength.

[0010] In the embodiments of the present application, by acquiring the actual radio frequency field intensity of each position in the scanning object at two preset radio frequency field strengths, the actual CEST signal intensity at the chemical shift of glutamate and the actual CEST signal intensity at the chemical shift opposite to the water molecule of glutamate, and based on the actual radio frequency field intensity and the actual CEST signal intensity at the chemical shift of glutamate of the same position at the two preset radio frequency field strengths, the CEST signal intensity of the position at the target radio frequency field strength at the chemical shift of glutamate can be corrected, so as to obtain the ideal CEST signal intensity of the position at the target radio frequency field strength at the chemical shift of glutamate, and the correction of the radio frequency field inhomogeneity is realized. Based on the actual radio frequency field intensity and the actual CEST signal intensity at the chemical shift opposite to the water molecule of glutamate of the same position at the two preset radio frequency field strengths, the CEST signal intensity of the position at the target radio frequency field strength at the chemical shift opposite to the water molecule of glutamate can be corrected, so as to obtain the ideal CEST signal intensity of the position at the target radio frequency field strength at the chemical shift opposite to the water molecule of glutamate, and the correction of the radio frequency field inhomogeneity is realized. Based on the above two ideal CEST signal intensities of the same position at the target radio frequency field strength, the Glu CEST signal intensity of the position at the target radio frequency field strength can be accurately measured.

[0011] In a second aspect, the embodiments of the present application provide a radio frequency field inhomogeneity correction device, comprising:

[0012] The first acquisition module is configured to acquire, when the radio frequency field intensity is a first preset radio frequency field intensity, first actual radio frequency field intensities at positions in a scanning object, a first actual chemical exchange saturation transfer (CEST) signal intensity at a first chemical shift, and a second actual CEST signal intensity at a second chemical shift, the first chemical shift being a chemical shift of glutamate, the second chemical shift being a chemical shift opposite to a water molecule relative to the glutamate, and the second preset radio frequency field intensity being different from the first preset radio frequency field intensity.

[0013] The second acquisition module is configured to acquire, when the radio frequency field intensity is a second preset radio frequency field intensity, second actual radio frequency field intensities at the positions in the scanning object, a third actual CEST signal intensity at the first chemical shift, and a fourth actual CEST signal intensity at the second chemical shift.

[0014] The first determination module is configured to determine, based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at a same position, a first ideal CEST signal intensity at the first chemical shift at a target radio frequency field intensity corresponding to the position.

[0015] The second determination module is configured to determine, based on the first actual radio frequency field intensity, the second actual CEST signal intensity, the second actual radio frequency field intensity, and the fourth actual CEST signal intensity at the same position, a second ideal CEST signal intensity at the second chemical shift at the target radio frequency field intensity corresponding to the position.

[0016] The third determination module is configured to determine, based on the first ideal CEST signal intensity and the second ideal CEST signal intensity at the target radio frequency field intensity of the same position, a glutamate (Glu) CEST signal intensity at the target radio frequency field intensity corresponding to the position.

[0017] In a third aspect, an electronic device is provided, which includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor. When the processor executes the computer program, the electronic device implements the radio frequency field inhomogeneity correction method according to any one of the first aspect.

[0018] In a fourth aspect, a computer readable storage medium is provided, which stores a computer program. When the computer program is executed by a computer, the radio frequency field inhomogeneity correction method according to the first aspect is implemented.

[0019] In a fifth aspect, an embodiment of the present application provides a computer program product, comprising a computer program, which, when executed by a computer, causes the radio frequency field inhomogeneity correction method according to any one of the first aspect to be performed.

[0020] It can be understood that the beneficial effects of the second aspect to the fifth aspect can be referred to the related description in the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0022] Figure 1 is a flowchart of the radio frequency field inhomogeneity correction method provided by the embodiments of the present application;

[0023] Figure 2 is a distribution diagram of the brain GluCEST signal intensity before correction provided by the embodiments of the present application;

[0024] Figure 3 is an example diagram of the radio frequency field correction result based on the first linear function provided by the embodiments of the present application;

[0025] Figure 4 is an example diagram of the radio frequency field correction result based on the second linear function provided by the embodiments of the present application;

[0026] Figure 5 is a distribution diagram of the brain GluCEST signal intensity after correction provided by the embodiments of the present application;

[0027] Figure 6 is a structural schematic diagram of the radio frequency field inhomogeneity correction device provided by the embodiments of the present application;

[0028] Figure 7 is a structural schematic diagram of the electronic device provided by the embodiments of the present application. DETAILED DESCRIPTION

[0029] In the following description, specific details such as specific system structures, techniques, etc. are presented in order to thoroughly understand the embodiments of the present application. However, it should be clear to those skilled in the art that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits and methods are omitted in order not to obscure the description of the present application with unnecessary details.

[0030] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0031] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0032] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0033] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0034] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0035] The radio frequency field non-uniformity correction method provided in this application embodiment can be applied to electronic devices such as mobile phones, tablets, magnetic resonance imaging equipment, laptops, ultra-mobile personal computers (UMPCs), netbooks, and personal digital assistants (PDAs). This application embodiment does not impose any restrictions on the specific type of electronic device.

[0036] Please see Figure 1 , Figure 1A flowchart of the method for correcting radio frequency field inhomogeneity is shown, which includes the following steps:

[0037] In step 101, the first actual radio frequency field intensity at each position in the scanning object, the first actual CEST signal intensity at the first chemical shift, and the second actual CEST signal intensity at the second chemical shift are obtained when the radio frequency field intensity is the first preset radio frequency field intensity.

[0038] The first chemical shift is the chemical shift of glutamate, which is usually 3ppm. The second chemical shift is the chemical shift of glutamate relative to the opposite side of the water molecule, which is usually -3ppm. It should be understood that the chemical shift can be understood as a frequency offset.

[0039] The scanning object is the scanning object of the magnetic resonance imaging device, and the specific type of the scanning object is not limited in the present application. As an example but not limitation, the scanning object is the brain of a human or an animal. Since the brain is three-dimensional, a certain layer or a certain slice of the brain can be selected for imaging, i.e., a certain layer or a certain slice of the brain is scanned.

[0040] When the radio frequency field intensity of the magnetic resonance imaging device is the first preset radio frequency field intensity, the actual radio frequency field intensity at each position in the scanning object usually deviates from the first preset radio frequency field intensity due to the obvious radio frequency field inhomogeneity of the magnetic resonance imaging device under high magnetic field intensity, or the actual radio frequency field intensity at some positions in the scanning object deviates from the first preset radio frequency field intensity. On this basis, the actual CEST signal intensity at the first chemical shift may be different from the ideal CEST signal intensity at the first chemical shift when the actual radio frequency field intensity at the corresponding position reaches the first preset radio frequency field intensity, and the actual CEST signal intensity at the second chemical shift may be different from the ideal CEST signal intensity at the second chemical shift when the actual radio frequency field intensity at the corresponding position reaches the first preset radio frequency field intensity. Therefore, the electronic device can perform step 101 to correct the radio frequency field inhomogeneity based on the data obtained in step 101 to achieve accurate measurement of GluCEST signal intensity. It should be understood that the measurement of GluCEST signal intensity can be understood as the quantification of GluCEST signal intensity.

[0041] In an embodiment, the electronic device can obtain a first relative spatial distribution map of the radio frequency field when the radio frequency field intensity is the first preset radio frequency field intensity. The first relative spatial distribution map includes the ratio of the first actual radio frequency field intensity at each position in the scanning object to the first preset radio frequency field intensity. Therefore, the first preset radio frequency field intensity multiplied by the first relative spatial distribution map can obtain the first actual radio frequency field intensity at each position in the scanning object.

[0042] In a possible implementation, for any position in the scanning object, the first actual CEST signal strength and the second actual CEST signal strength at the position are acquired in the following manner:

[0043] In the case where the radio frequency field strength is the first preset radio frequency field strength, a first radio frequency pulse-labeled magnetic resonance signal strength image at the first chemical shift and a second radio frequency pulse-labeled magnetic resonance signal strength image at the second chemical shift are acquired.

[0044] The first actual CEST signal strength is determined from the first radio frequency pulse-labeled magnetic resonance signal strength image.

[0045] The second actual CEST signal strength is determined from the second radio frequency pulse-labeled magnetic resonance signal strength image.

[0046] The first radio frequency pulse-labeled magnetic resonance signal strength image includes the radio frequency pulse-labeled magnetic resonance signal strength at the first chemical shift of each position in the scanning object in the case where the radio frequency field strength is the first preset radio frequency field strength. For any position in the scanning object, the radio frequency pulse-labeled magnetic resonance signal strength of the position at the first chemical shift in the first radio frequency pulse-labeled magnetic resonance signal strength image can be determined as the first actual CEST signal strength.

[0047] The second radio frequency pulse-labeled magnetic resonance signal strength image includes the radio frequency pulse-labeled magnetic resonance signal strength at the second chemical shift of each position in the scanning object in the case where the radio frequency field strength is the first preset radio frequency field strength. For any position in the scanning object, the radio frequency pulse-labeled magnetic resonance signal strength of the position at the second chemical shift in the second radio frequency pulse-labeled magnetic resonance signal strength image can be determined as the second actual CEST signal strength.

[0048] In the case where the radio frequency field strength is the second preset radio frequency field strength, the second actual radio frequency field strength of each position in the scanning object, the third actual CEST signal strength at the first chemical shift, and the fourth actual CEST signal strength at the second chemical shift are acquired.

[0049] The second preset radio frequency field strength is different from the first preset radio frequency field strength, i.e., the second preset radio frequency field strength is not equal to the first preset radio frequency field strength.

[0050] Optionally, the first preset radio frequency field strength and the second preset radio frequency field strength can be any two different radio frequency field strengths that are preset, and the specific values of the first preset radio frequency field strength and the second preset radio frequency field strength are not limited in the present application.

[0051] In a case where the radio frequency field strength of the magnetic resonance imaging device is the second preset radio frequency field strength, due to the obvious radio frequency field inhomogeneity of the magnetic resonance imaging device at a high magnetic field strength, the actual radio frequency field strength at each position in the scanning object usually deviates from the second preset radio frequency field strength, or the actual radio frequency field strength at some positions in the scanning object deviates from the second preset radio frequency field strength. On this basis, the actual CEST signal strength at the first chemical shift may be different from the ideal CEST signal strength at the first chemical shift when the actual radio frequency field strength at the corresponding position reaches the second preset radio frequency field strength, and the actual CEST signal strength at the second chemical shift may be different from the ideal CEST signal strength at the second chemical shift when the actual radio frequency field strength at the corresponding position reaches the second preset radio frequency field strength. Therefore, the electronic device can perform step 102 to perform radio frequency field inhomogeneity correction based on the data obtained in step 102, so as to realize accurate measurement of GluCEST signal strength.

[0052] In an embodiment, the electronic device can obtain a second relative spatial distribution map of the radio frequency field in a case where the radio frequency field strength is the second preset radio frequency field strength. The second relative spatial distribution map includes the ratio of the second actual radio frequency field strength at each position in the scanning object to the second preset radio frequency field strength. Therefore, multiplying the second preset radio frequency field strength by the second relative spatial distribution map can obtain the second actual radio frequency field strength at each position in the scanning object.

[0053] Optionally, the electronic device can obtain the first relative spatial distribution map and the second relative spatial distribution map of the radio frequency field by a TurboFLASH imaging method or a double-inversion-angle gradient echo imaging method.

[0054] It should be understood that the first relative spatial distribution map and the second relative spatial distribution map have the same imaging parameters as the actual CEST signal strength obtained in steps 101 and 102, such as imaging field of view, spatial resolution, shimming range, slice thickness, and the like.

[0055] In a possible implementation, for any position in the scanning object, the third actual CEST signal strength and the fourth actual CEST signal strength at the position are obtained in the following manner:

[0056] In a case where the radio frequency field strength is the second preset radio frequency field strength, a third radio frequency pulse-labeled magnetic resonance signal strength image at the first chemical shift and a fourth radio frequency pulse-labeled magnetic resonance signal strength image at the second chemical shift are obtained;

[0057] The third actual CEST signal strength is determined from the third radio frequency pulse-labeled magnetic resonance signal strength image;

[0058] determining a fourth actual CEST signal intensity from the fourth radio frequency pulse labeled magnetic resonance signal intensity image.

[0059] The third radio frequency pulse labeled magnetic resonance signal intensity image comprises the radio frequency pulse labeled magnetic resonance signal intensity at the first chemical shift of each position in the scanning object at the second preset radio frequency field strength. For any position in the scanning object, the radio frequency pulse labeled magnetic resonance signal intensity at the first chemical shift of the position in the third radio frequency pulse labeled magnetic resonance signal intensity image can be determined as the third actual CEST signal intensity.

[0060] The fourth radio frequency pulse labeled magnetic resonance signal intensity image comprises the radio frequency pulse labeled magnetic resonance signal intensity at the second chemical shift of each position in the scanning object at the second preset radio frequency field strength. For any position in the scanning object, the radio frequency pulse labeled magnetic resonance signal intensity at the second chemical shift of the position in the fourth radio frequency pulse labeled magnetic resonance signal intensity image can be determined as the fourth actual CEST signal intensity.

[0061] In step 103, based on the first actual radio frequency field strength, the first actual CEST signal intensity, the second actual radio frequency field strength and the third actual CEST signal intensity of the same position, a first ideal CEST signal intensity at the first chemical shift of the corresponding position at the target radio frequency field strength is determined.

[0062] Optionally, the target radio frequency field strength can be at least one of the first preset radio frequency field strength and the second preset radio frequency field strength, or a radio frequency field strength different from the first preset radio frequency field strength and the second preset radio frequency field strength. As an example but not limitation, the target radio frequency field strength can be any radio frequency field strength or at least one radio frequency field strength in the range of 2 μT ~ 5 μT.

[0063] For any position in the scanning object, the first ideal CEST signal intensity at the first chemical shift of the position at the target radio frequency field strength can refer to the CEST signal intensity at the first chemical shift of the position when the radio frequency field strength of the position is the target radio frequency field strength or reaches the target radio frequency field strength (i.e. the CEST signal intensity at the first chemical shift of the position that can be reached in the absence of the inhomogeneity of the radio frequency field or without considering the inhomogeneity of the radio frequency field).

[0064] As an example but not limitation, the target radio frequency field strength is 3.5 μT, but the actual radio frequency field strength at a certain position in the scanned object is 2 μT, then the actual CEST signal strength of the position at the first chemical shift is not the first ideal CEST signal strength (i.e. the CEST signal strength of the position at the first chemical shift when the actual radio frequency field strength at the position is 3.5 μT) that is desired, and the electronic device can correct the actual CEST signal strength of the position to the first ideal CEST signal strength through the above step 103.

[0065] In a possible implementation, the above step 103 comprises:

[0066] For any position in the scanned object, based on the first actual radio frequency field strength, the first actual CEST signal strength, the second actual radio frequency field strength and the third actual CEST signal strength at the position, the coefficient of the first linear function of the reciprocal of the CEST signal strength of the position at the first chemical shift and the radio frequency field strength is solved.

[0067] In the case where the coefficient of the first linear function is solved, the first ideal CEST signal strength is determined based on the target radio frequency field strength and the first linear function.

[0068] Before performing step 103, the electronic device can first construct a first linear function for each position in the scanned object (i.e. different positions in the scanned object correspond to a first linear function respectively), at this time the coefficient of the first linear function is an unknown quantity. Then for any position in the scanned object, the coefficient of the first linear function corresponding to the position can be solved through the above implementation, and after the coefficient of the first linear function is solved, the target radio frequency field strength is substituted into the first linear function with the known coefficient to obtain the first ideal CEST signal strength.

[0069] Step 104, based on the first actual radio frequency field strength, the second actual CEST signal strength, the second actual radio frequency field strength and the fourth actual CEST signal strength at the same position, the second ideal CEST signal strength of the corresponding position at the second chemical shift under the target radio frequency field strength is determined.

[0070] For any position in the scanned object, the second ideal CEST signal strength of the position at the second chemical shift under the target radio frequency field strength can refer to the CEST signal strength of the position at the second chemical shift when the radio frequency field strength at the position is the target radio frequency field strength or reaches the target radio frequency field strength (i.e. the CEST signal strength of the position at the second chemical shift in the absence of the inhomogeneity of the radio frequency field or without considering the inhomogeneity of the radio frequency field).

[0071] As an example but not limitation, the target radio frequency field strength is 3.5 μT, but the actual radio frequency field strength at a certain position in the scanned object is 2 μT, then the actual CEST signal strength at the second chemical shift of this position is not the second ideal CEST signal strength (i.e. the CEST signal strength at the second chemical shift when the actual radio frequency field strength at this position is 3.5 μT) that is desired, and the electronic device can correct the actual CEST signal strength of this position to the second ideal CEST signal strength through the above step 103.

[0072] Step 105, based on the first ideal CEST signal strength and the second ideal CEST signal strength of the same position under the target radio frequency field strength, determine the GluCEST signal strength of the corresponding position under the target radio frequency field strength.

[0073] In a possible implementation, the above step 105 comprises:

[0074] For any position in the scanned object, determine the difference between the second ideal CEST signal strength and the first ideal CEST signal strength of the position under the target radio frequency field strength;

[0075] Determine the ratio of the difference to the second ideal CEST signal strength as the GluCEST signal strength of the position under the target radio frequency field strength;

[0076] Or, determine the ratio of the difference to the radio frequency pulse-free labeled magnetic resonance signal strength at the position as the GluCEST signal strength of the position under the target radio frequency field strength.

[0077] For any position in the scanned object, the first ideal CEST signal strength contains the signal attenuation of water molecules caused by glutamate, and the second ideal CEST signal strength does not contain the signal attenuation of water molecules caused by glutamate. On this basis, subtract the second ideal CEST signal strength from the first ideal CEST signal strength, and divide the difference by the radio frequency pulse-free labeled magnetic resonance signal strength or the second ideal CEST signal strength to obtain the GluCEST signal strength, thereby achieving accurate measurement of the GluCEST signal strength.

[0078] The brain experiment test of the embodiment proves that the correction of radio frequency field inhomogeneity can be achieved, and accurate measurement of the GluCEST signal strength can be achieved.

[0079] In the brain implementation test, the preset radio frequency field strength (i.e. Figure 2 The GluCEST signal strength is determined by the following formula: The glutathione levels were 3.5 μT, 4 μT (i.e., 4.0 μT), and 4.5 μT, respectively; the saturation time was 800 ms; the repetition time was 5 s; and the chemical shifts were ±3.3 ppm, ±3 ppm, and ±2.7 ppm, respectively. The distributions of brain GluCEST signal intensities corresponding to 3.5 μT, 4 μT, and 4.5 μT are shown below. Figure 2 As shown, the white matter region was segmented from the magnetic resonance signal intensity image without radio frequency pulse markers using a thresholding method. Three regions of interest (ROIs) were defined based on the range of change of the actual radio frequency field intensity within the white matter region compared to 100% (i.e., the preset radio frequency field intensity): ROI1 was the region with an absolute change of less than 10%, ROI2 was the region with an absolute change between 10% and 20%, and ROI3 was the region with an absolute change of more than 20%. The average GluCEST signal intensity at each location within the region with an absolute change of less than 2% was selected as the reference intensity. When the preset RF field strength is 3.5 μT, the reference strength is 8.23 ​​± 1.12%, and the GluCEST signal strengths of the three ROIs are 7.54 ± 0.88%, 5.87 ± 0.82%, and 3.48 ± 0.44%, respectively. When the preset RF field strength is 4 μT, the reference strength is 10.03 ± 1.28%, and the GluCEST signal strengths of the three ROIs are 9.37 ± 1.01%, 7.92 ± 0.96%, and 5.72 ± 0.16%, respectively. When the preset RF field strength is 4.5 μT, the reference strength is 11.50 ± 1.44%, and the GluCEST signal strengths of the three ROIs are 11.08 ± 1.10%, 9.94 ± 0.97%, and 7.77 ± 0.42%, respectively. This shows that the GluCEST signal intensity at different ROIs differs significantly from the reference intensity, confirming that radio frequency field inhomogeneity affects the accuracy of GluCEST signal intensity measurements. Figure 2 The range 0 to 18 represents the variation range of the actual radio frequency field strength compared to 100%, expressed as a percentage. Figure 2 The 18 in the text represents 18%. (By...) Figure 2 It can be seen that when the preset radio frequency field intensities are 3.5μT, 4μT and 4.5μT, the spatial distribution of GluCEST signal intensity in the same tissue in the brain is significantly different due to the non-uniformity of the radio frequency field.

[0080] Based on the constructed first linear function 1 / Z(+ 3ppm) = C0 + C1 *B1 and the second linear function 1 / Z(-3ppm) = C2 + C3 *B1, * is a multiplication sign, Z(+ 3ppm) is the CEST signal intensity at the first chemical shift, Z(- 3ppm) is the CEST signal intensity at the second chemical shift, B1 in the first linear function and the second linear function is the radio frequency field intensity, the coefficients C0, C1 in the first linear function and the coefficients C2 and C3 in the second linear function can be obtained from the actual radio frequency field intensity and the corresponding actual CEST signal intensity, and then the ideal CEST signal intensity at + 3ppm and - 3ppm is obtained, thereby solving the influence of radio frequency field inhomogeneity on the measurement of GluCEST signal intensity. Two radio frequency field intensities of 4μT and 4.5μT are taken as the preset radio frequency field intensity and the target radio frequency field intensity for two-point radio frequency field correction, and three radio frequency field intensities of 3.5μT, 4μT and 4.5μT are taken as the preset radio frequency field intensity and the target radio frequency field intensity for three-point radio frequency field correction. As shown in FIG. 8, it is a radio frequency field correction result example diagram based on the first linear function. Figure 3 As shown in FIG. 9, it is a radio frequency field correction result example diagram based on the second linear function. Figure 4 As shown in FIG. 10, it is a radio frequency field correction result example diagram based on the first linear function and the second linear function.

[0081] For any position in the white matter region of the brain, Figure 3 the abscissa of A1 in the above formula represents the actual radio frequency field intensity of the position when the radio frequency field intensity of the radio frequency field is 3.5μT, and the ordinate represents the actual CEST signal intensity of the position at the first chemical shift under the actual radio frequency field intensity; Figure 3 the abscissa of A2 in the above formula represents the actual radio frequency field intensity of the position when the radio frequency field intensity of the radio frequency field is 4μT, and the ordinate represents the actual CEST signal intensity of the position at the first chemical shift under the actual radio frequency field intensity; Figure 3 the abscissa of A3 in the above formula represents the target radio frequency field intensity of the position, and the ordinate represents the ideal CEST signal intensity of the position at the first chemical shift under 3.5μT; Figure 3 the abscissa of A4 in the above formula represents the actual radio frequency field intensity of the position when the radio frequency field intensity of the radio frequency field is 4.5μT, and the ordinate represents the actual CEST signal intensity of the position at the first chemical shift under the actual radio frequency field intensity; Figure 3 the abscissa of A5 in the above formula represents the target radio frequency field intensity of the position, and the ordinate represents the ideal CEST signal intensity of the position at the first chemical shift under 4μT; Figure 3 the abscissa of A6 in the above formula represents the target radio frequency field intensity of the position, and the ordinate represents the ideal CEST signal intensity of the position at the first chemical shift under 4.5μT.

[0082] It should be noted that, Figure 3 The yellow line in coincides with the green line, and the circle on the yellow line is used to describe A5 when two-point radio frequency field correction is performed, and the circle on the green line is used to describe A5 when three-point radio frequency correction is performed. Figure 3 The cyan line in coincides with the blue line, and the circle on the cyan line is used to describe A6 when two-point radio frequency field correction is performed, and the circle on the blue line is used to describe A6 when three-point radio frequency correction is performed. Figure 3 The black dashed line in represents a first linear function fitted by A2 and A4, and the black solid line represents a first linear function fitted based on A1, A2 and A4.

[0083] For any position in the white matter region of the brain, Figure 4 The abscissa of D1 in represents the actual radio frequency field strength of the position when the radio frequency field strength of the radio frequency field is 3.5 μT, and the ordinate represents the actual CEST signal radio frequency field strength of the position at the second chemical shift under the actual radio frequency field strength; Figure 4 The abscissa of D2 in represents the actual radio frequency field strength of the position when the radio frequency field strength of the radio frequency field is 4 μT, and the ordinate represents the actual CEST signal strength of the position at the second chemical shift under the actual radio frequency field strength; Figure 4 The abscissa of D3 in represents the target radio frequency field strength of the position is 3.5 μT, and the ordinate represents the ideal CEST signal strength of the position at the second chemical shift under 3.5 μT; Figure 4 The abscissa of D4 in represents the actual radio frequency field strength of the position when the radio frequency field strength of the radio frequency field is 4.5 μT, and the ordinate represents the actual CEST signal strength of the position at the second chemical shift under the actual radio frequency field strength; Figure 4 The abscissa of D5 in represents the target radio frequency field strength of the position is 4 μT, and the ordinate represents the ideal CEST signal strength of the position at the second chemical shift under 4 μT; Figure 4 The abscissa of D6 in represents the target radio frequency field strength of the position is 4.5 μT, and the ordinate represents the ideal CEST signal strength of the position at the second chemical shift under 4.5 μT.

[0084] It should be noted that, Figure 4 The yellow line in coincides with the green line, and the circle on the yellow line is used to describe D5 when two-point radio frequency field correction is performed, and the circle on the green line is used to describe D5 when three-point radio frequency correction is performed. Figure 4 The cyan line in coincides with the blue line, and the circle on the cyan line is used to describe D6 when two-point radio frequency field correction is performed, and the circle on the blue line is used to describe D6 when three-point radio frequency correction is performed. Figure 4The black dashed line in FIG. 6 represents the second linear function fitted by D2 and D4, and the black solid line represents the second linear function fitted based on D1, D2 and D4.

[0085] It can be seen from FIG. 6 that the results obtained by the two-point RF field correction and the three-point RF field correction are close, which proves that the RF field correction method provided in the embodiment has good stability and can correct the RF field based on the magnetic resonance data of two preset RF field strengths. Figure 3 and Figure 4 It can be seen that the results obtained by the two-point RF field correction and the three-point RF field correction are close, which proves that the RF field correction method provided in the embodiment has good stability and can correct the RF field based on the magnetic resonance data of two preset RF field strengths.

[0086] After the RF field inhomogeneity correction is implemented based on the embodiment, the distribution of the brain GluCEST signal intensity is as shown in FIG. 7. Figure 5 Figure 5 In FIG. 7, 3.5 μT, 4 μT and 4.5 μT are preset RF field strengths, and the three preset RF field strengths are taken as target RF field strengths to facilitate comparison of the results before and after correction. Figure 5 represents two-point RF field correction, represents three-point RF field correction. When the preset RF field strength is 3.5 μT, the GluCEST signal intensities of the three ROIs in the two-point RF field correction are 8.34 ± 0.91 %, 8.61 ± 0.92 % and 8.69 ± 0.93 % respectively, and the GluCEST signal intensities of the three ROIs in the three-point RF field correction are 8.27 ± 0.92 %, 8.52 ± 0.95 % and 8.63 ± 0.96 % respectively. When the preset RF field strength is 4 μT, the GluCEST signal intensities of the three ROIs in the two-point RF field correction are 10.24 ± 1.05 %, 10.49 ± 1.01 % and 10.39 ± 1.01 % respectively, and the GluCEST signal intensities of the three ROIs in the three-point RF field correction are 10.18 ± 1.05 %, 10.42 ± 1.02 % and 10.34 ± 1.03 % respectively. When the preset RF field strength is 4.5 μT, the GluCEST signal intensities of the three ROIs in the two-point RF field correction are 11.65 ± 1.17 %, 11.91 ± 1.09 % and 11.69 ± 1.10 % respectively, and the GluCEST signal intensities of the three ROIs in the three-point RF field correction are 11.59 ± 1.17 %, 11.84 ± 1.10 % and 11.65 ± 1.11 % respectively. After the RF field correction, the differences between the GluCEST signal intensities of the three ROIs and the reference intensity at the preset RF field strengths of 3.5 μT, 4 μT and 4.5 μT are much smaller than before the RF field correction. It can be seen that the RF field correction scheme provided in the embodiment effectively improves the influence of RF field inhomogeneity on the measurement of GluCEST signal intensity.

[0087] It can be seen from FIG. 6 that the results obtained by the two-point RF field correction and the three-point RF field correction are close, which proves that the RF field correction method provided in the embodiment has good stability and can correct the RF field based on the magnetic resonance data of two preset RF field strengths. Figure 5 ​​It can be seen that the same tissue signal of the brain is more uniform than before correction, and the correction results obtained by two-point radio frequency field correction and three-point radio frequency field correction under three target radio frequency field intensities are similar, which confirms that the radio frequency field correction method provided in the embodiment has good stability, and radio frequency field inhomogeneity can be corrected based on magnetic resonance data under two different preset radio frequency field intensities.

[0088] In the embodiment of the application, by acquiring the actual radio frequency field intensity of each position in the scanning object under two preset radio frequency field intensities, the actual CEST signal intensity at the chemical shift of glutamate, and the actual CEST signal intensity at the chemical shift opposite to the water molecule of glutamate, and based on the actual radio frequency field intensity and the actual CEST signal intensity at the chemical shift of glutamate of the same position under two preset radio frequency field intensities, the CEST signal intensity of the position at the chemical shift of glutamate under the target radio frequency field intensity can be corrected, so as to obtain the ideal CEST signal intensity of the position at the chemical shift of glutamate under the target radio frequency field intensity, and the correction of radio frequency field inhomogeneity is realized. Based on the actual radio frequency field intensity and the actual CEST signal intensity at the chemical shift opposite to the water molecule of glutamate of the same position under two preset radio frequency field intensities, the CEST signal intensity of the position at the chemical shift opposite to the water molecule of glutamate under the target radio frequency field intensity can be corrected, so as to obtain the ideal CEST signal intensity of the position at the chemical shift opposite to the water molecule of glutamate under the target radio frequency field intensity, and the correction of radio frequency field inhomogeneity is realized. Based on the above two ideal CEST signal intensities of the same position under the target radio frequency field intensity, the GluCEST signal intensity of the position under the target radio frequency field intensity can be accurately measured.

[0089] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiment of the application.

[0090] Corresponding to the radio frequency field inhomogeneity correction method described in the above embodiment, Figure 6 The structure schematic diagram of the radio frequency field inhomogeneity correction device provided in the embodiment of the application is shown, and only the part related to the embodiment of the application is shown for ease of illustration.

[0091] With reference to Figure 6 The device comprises:

[0092] ​The first acquisition module 601 is configured to acquire, in a case where a radio frequency field intensity of a radio frequency field is a first preset radio frequency field intensity, a first actual radio frequency field intensity at each position in a scanning object, a first actual chemical exchange saturation transfer (CEST) signal intensity at a first chemical shift, and a second actual CEST signal intensity at a second chemical shift, the first chemical shift being a chemical shift of glutamate, and the second chemical shift being a chemical shift opposite to a water molecule relative to the glutamate;

[0093] The second acquisition module 602 is configured to acquire, in a case where the radio frequency field intensity of the radio frequency field is a second preset radio frequency field intensity, a second actual radio frequency field intensity at each position in the scanning object, a third actual CEST signal intensity at the first chemical shift, and a fourth actual CEST signal intensity at the second chemical shift, the second preset radio frequency field intensity being different from the first preset radio frequency field intensity.

[0094] The first determination module 603 is configured to determine, based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at a same position, a first ideal CEST signal intensity at the first chemical shift of a corresponding position under a target radio frequency field intensity.

[0095] The second determination module 604 is configured to determine, based on the first actual radio frequency field intensity, the second actual CEST signal intensity, the second actual radio frequency field intensity, and the fourth actual CEST signal intensity at the same position, a second ideal CEST signal intensity at the second chemical shift of the corresponding position under the target radio frequency field intensity.

[0096] The third determination module 605 is configured to determine, based on the first ideal CEST signal intensity and the second ideal CEST signal intensity of the same position under the target radio frequency field intensity, a glutamate (Glu) CEST signal intensity of the corresponding position under the target radio frequency field intensity.

[0097] Optionally, the first determination module 603 is specifically configured to:

[0098] For any position in the scanning object, based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at the position, a coefficient of a first linear function of an inverse of a CEST signal intensity and a radio frequency field intensity of the position at the first chemical shift is solved.

[0099] In a case where the coefficient of the first linear function is solved, based on the target radio frequency field intensity and the first linear function, the first ideal CEST signal intensity is determined.

[0100] Optionally, the second determining module 604 is specifically used for:

[0101] For any position in the scanning object, based on the first actual radio frequency field strength, the second actual CEST signal strength, the second actual radio frequency field strength and the fourth actual CEST signal strength at the position, a coefficient of a second linear function of the CEST signal strength and the radio frequency field strength at the position at the second chemical shift is solved.

[0102] In a case where the coefficient of the second linear function is solved, based on the target radio frequency field strength and the second linear function, the second ideal CEST signal strength is determined.

[0103] Optionally, the third determining module 605 is specifically used for:

[0104] For any position in the scanning object, a difference between the second ideal CEST signal strength and the first ideal CEST signal strength of the position at the target radio frequency field strength is determined.

[0105] A ratio of the difference and the second ideal CEST signal strength is determined as a GluCEST signal strength of the position at the target radio frequency field strength.

[0106] Or, a ratio of the difference and a radio frequency pulse-free labeled magnetic resonance signal strength at the position is determined as the GluCEST signal strength of the position at the target radio frequency field strength.

[0107] Optionally, the first acquiring module 601 is specifically used for:

[0108] In a case where a radio frequency field strength of the radio frequency field is the first preset radio frequency field strength, a first radio frequency pulse-labeled magnetic resonance signal strength image at the first chemical shift and a second radio frequency pulse-labeled magnetic resonance signal strength image at the second chemical shift are acquired.

[0109] The first actual CEST signal strength is determined from the first radio frequency pulse-labeled magnetic resonance signal strength image.

[0110] The second actual CEST signal strength is determined from the second radio frequency pulse-labeled magnetic resonance signal strength image.

[0111] Optionally, the second acquiring module 602 is specifically used for:

[0112] In a case where the radio frequency field intensity of the radio frequency field is the second preset radio frequency field intensity, acquire a third radio frequency pulse-labeled magnetic resonance signal intensity image at the first chemical shift and a fourth radio frequency pulse-labeled magnetic resonance signal intensity image at the second chemical shift;

[0113] determine the third actual CEST signal intensity from the third radio frequency pulse-labeled magnetic resonance signal intensity image;

[0114] determine the fourth actual CEST signal intensity from the fourth radio frequency pulse-labeled magnetic resonance signal intensity image.

[0115] It should be noted that the information interaction, execution process and the like between the above apparatuses / units are based on the same concept as the method embodiments of the present application, and specific functions and brought technical effects can be referred to the method embodiments part, which will not be repeated here.

[0116] Figure 7 The structure schematic diagram of the electronic device provided by the embodiments of the present application is shown in the figure. Figure 7 As shown in the figure, the electronic device 7 of the embodiments includes at least one processor 70 (only one is shown in the figure), a memory 71, and a computer program 72 stored in the memory 71 and executable on the at least one processor 70, wherein the processor 70 executes the computer program 72 to implement the steps in any of the above method embodiments. Figure 7

[0117] The electronic device can include, but is not limited to, the processor 70 and the memory 71. Those skilled in the art can understand that, Figure 7 The electronic device 7 is only an example and does not constitute a limitation on the electronic device 7, which can include more or fewer components than shown, or combine certain components, or different components, for example, it can also include input / output devices, network access devices, etc.

[0118] The processor 70 can be a central processing unit (CPU), and the processor 70 can also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0119] ​The memory 71 can be an internal storage unit of the electronic device 7 in some embodiments, such as a hard disk or a memory of the electronic device 7. The memory 71 can also be an external storage device of the electronic device 7 in other embodiments, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 7. Further, the memory 71 can include both an internal storage unit and an external storage device of the electronic device 7. The memory 71 is used to store an operating system, an application program, a boot loader, data, and other programs, such as program codes of the computer program, etc. The memory 71 can also be used to temporarily store data that has been output or will be output.

[0120] It can be clearly understood by those skilled in the art that, for the convenience and brevity of description, only the above division of functional units and modules is taken as an example, and in actual application, the above functions can be completed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to complete all or part of the above-described functions. Each functional unit and module in the embodiment can be integrated in one processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit, and the integrated unit can be realized in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for convenient distinction, and do not limit the protection scope of the present application. The specific working process of the units and modules in the above system can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0121] The integrated unit, if implemented in the form of a software function unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, the present application can implement all or part of the processes in the above-mentioned embodiment methods through a computer program to instruct related hardware to complete, and the computer program can be stored in a computer readable storage medium. When the processor executes the computer program, the steps of each method embodiment described above can be implemented. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms. The computer readable medium at least includes any entity or device capable of carrying the computer program code to the device / equipment, recording medium, computer memory, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), electrical carrier signal, telecommunication signal and software distribution medium. For example, U disk, mobile hard disk, magnetic disk or optical disk, etc.

[0122] In the above embodiments, the description of each embodiment has its own focus, and the parts not described or recorded in detail in a certain embodiment can be referred to the related description of other embodiments.

[0123] Those skilled in the art can appreciate that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0124] In the embodiments provided by the present application, it should be understood that the disclosed apparatus / equipment and method can be implemented in other ways. For example, the above-described apparatus / equipment embodiments are only schematic, and the division of the modules or units is only a logical function division, and there can be another division manner in actual implementation, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection between each of them can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

[0125] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may also be distributed to multiple network units. Part or all of the units can be selected to achieve the purpose of the embodiment scheme according to actual needs.

[0126] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A radio frequency field inhomogeneity correction method, characterized by, The method comprises: In the case where the radio frequency field intensity is a first preset radio frequency field intensity, acquiring a first actual radio frequency field intensity at each position in a scanning object, a first actual chemical exchange saturation transfer (CEST) signal intensity at a first chemical shift, and a second actual CEST signal intensity at a second chemical shift, the first chemical shift being a chemical shift of glutamate, and the second chemical shift being a chemical shift opposite to that of a water molecule relative to the glutamate; In the case where the radio frequency field intensity is a second preset radio frequency field intensity, acquiring a second actual radio frequency field intensity at each position in the scanning object, a third actual CEST signal intensity at the first chemical shift, and a fourth actual CEST signal intensity at the second chemical shift, the second preset radio frequency field intensity being different from the first preset radio frequency field intensity; Based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at the same position, determining a first ideal CEST signal intensity at the first chemical shift under a target radio frequency field intensity at the corresponding position; Based on the first actual radio frequency field intensity, the second actual CEST signal intensity, the second actual radio frequency field intensity, and the fourth actual CEST signal intensity at the same position, determining a second ideal CEST signal intensity at the second chemical shift under the target radio frequency field intensity at the corresponding position; Based on the first ideal CEST signal intensity and the second ideal CEST signal intensity under the target radio frequency field intensity at the same position, determining a glutamate (Glu) CEST signal intensity under the target radio frequency field intensity at the corresponding position.

2. The radio frequency field inhomogeneity correction method of claim 1, wherein, The method comprises: For any position in the scanning object, based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at the position, solving a coefficient of a first linear function of the reciprocal of the CEST signal intensity and the radio frequency field intensity at the first chemical shift of the position; In the case where the coefficient of the first linear function is solved, based on the target radio frequency field intensity and the first linear function, determining the first ideal CEST signal intensity.

3. The radio frequency field inhomogeneity correction method of claim 1, wherein, The method comprises: solving, for any position in the scanning object, a coefficient of a second linear function of a reciprocal of a CEST signal strength and a radio frequency field strength of the position at the second chemical shift based on the first actual radio frequency field strength, the second actual CEST signal strength, the second actual radio frequency field strength and the fourth actual CEST signal strength at the position; determining, in a case that the coefficient of the second linear function is solved, the second ideal CEST signal strength based on the target radio frequency field strength and the second linear function.

4. The radio frequency field inhomogeneity correction method of any one of claims 1 to 3, characterized in that, the determining, based on the first ideal CEST signal strength and the second ideal CEST signal strength of the same position at the target radio frequency field strength, of a glutamate (Glu) CEST signal strength of the corresponding position at the target radio frequency field strength, comprises: determining, for any position in the scanning object, a difference between the second ideal CEST signal strength and the first ideal CEST signal strength of the position at the target radio frequency field strength; determining a ratio of the difference to the second ideal CEST signal strength as the Glu CEST signal strength of the position at the target radio frequency field strength; or, determining a ratio of the difference to a radio frequency pulse-free labeled magnetic resonance signal strength of the position as the Glu CEST signal strength of the position at the target radio frequency field strength.

5. The radio frequency field inhomogeneity correction method according to any one of claims 1 to 3, characterized in that, the acquiring, for any position in the scanning object, of the first actual CEST signal strength and the second actual CEST signal strength at the position, comprises: acquiring, in a case that the radio frequency field strength is the first preset radio frequency field strength, a first radio frequency pulse-labeled magnetic resonance signal strength image at the first chemical shift and a second radio frequency pulse-labeled magnetic resonance signal strength image at the second chemical shift; determining the first actual CEST signal strength from the first radio frequency pulse-labeled magnetic resonance signal strength image; determining the second actual CEST signal strength from the second radio frequency pulse-labeled magnetic resonance signal strength image.

6. The radio frequency field inhomogeneity correction method of any one of claims 1 to 3, wherein, the acquiring, for any position in the scanning object, of the third actual CEST signal strength and the fourth actual CEST signal strength at the position, comprises: acquiring, in a case that the radio frequency field strength is the second preset radio frequency field strength, a third radio frequency pulse-labeled magnetic resonance signal strength image at the first chemical shift and a fourth radio frequency pulse-labeled magnetic resonance signal strength image at the second chemical shift; determining the third actual CEST signal strength from the third radio frequency pulse-labeled magnetic resonance signal strength image; determining the fourth actual CEST signal strength from the fourth radio frequency pulse-labeled magnetic resonance signal strength image.

7. A radio frequency field inhomogeneity correction device, characterized by comprises: The first acquisition module is configured to acquire, in a case where the radio frequency field intensity is a first preset radio frequency field intensity, first actual radio frequency field intensities at positions in a scanning object, a first actual chemical exchange saturation transfer (CEST) signal intensity at a first chemical shift, and a second actual CEST signal intensity at a second chemical shift, the first chemical shift being a chemical shift of glutamate, and the second chemical shift being a chemical shift opposite to a water molecule relative to the glutamate; The second acquisition module is configured to acquire, in a case where the radio frequency field intensity is a second preset radio frequency field intensity, second actual radio frequency field intensities at the positions in the scanning object, a third actual CEST signal intensity at the first chemical shift, and a fourth actual CEST signal intensity at the second chemical shift, the second preset radio frequency field intensity being different from the first preset radio frequency field intensity; The first determination module is configured to determine, based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at a same position, a first ideal CEST signal intensity at the first chemical shift of a corresponding position under a target radio frequency field intensity; The second determination module is configured to determine, based on the first actual radio frequency field intensity, the second actual CEST signal intensity, the second actual radio frequency field intensity, and the fourth actual CEST signal intensity at the same position, a second ideal CEST signal intensity at the second chemical shift of the corresponding position under the target radio frequency field intensity; The third determination module is configured to determine, based on the first ideal CEST signal intensity and the second ideal CEST signal intensity of the same position under the target radio frequency field intensity, a glutamate (Glu) CEST signal intensity of the corresponding position under the target radio frequency field intensity.

8. The radio frequency field inhomogeneity correction device of claim 7, wherein, The first determination module is specifically configured to: For any position in the scanning object, based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at the position, a coefficient of a first linear function of an inverse of a CEST signal intensity and a radio frequency field intensity at the first chemical shift of the position is solved; In a case where the coefficient of the first linear function is solved, based on the target radio frequency field intensity and the first linear function, the first ideal CEST signal intensity is determined.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor executes the computer program, so that the electronic device implements the radio frequency field inhomogeneity correction method in any one of claims 1 to 6.

10. A computer program product, characterised in that, The computer program is executed, so that the radio frequency field inhomogeneity correction method in any one of claims 1 to 6 is performed.

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